The present invention relates to a roll clamp and, more particularly, to a swing frame roll clamping apparatus mountable on a vehicle for engaging, transporting and stacking rolls of paper and other materials.
Pivoting arm roll clamps for mounting on lift trucks and other vehicles are widely used in handling rolls of paper products, such as newsprint and kraft paper, and other materials. Typically, roll clamps are rotatable to engage, transport and deposit a roll with the longitudinal axis of the roll either vertical or horizontal. If the roll is lying on a surface with the axis of the roll horizontal, it is preferable that the arms at the top of the horizontally oriented clamping attachment extend forward of the lift vehicle further than the lower arms so that the upper arm can overreach the roll enabling the clamp pads at the ends of the upper and lower arms to engage the roll at diametrically opposed positions without requiring that the lower arm be pushed under the roll which is likely to cause it to roll away from the clamp. On the other hand, when a roll is transported or stacked with the longitudinal axis vertical, it is preferable that the arms on both sides of the roll extend equally far forward of the lift vehicle to facilitate inserting both arms between closely adjacent rolls without damaging them. Moving the clamp or the roll normal to the roll's longitudinal axis is also often useful to align the clamp or roll without moving the lift vehicle during stacking or during loading or unloading of a transport vehicle or to change the height of the roll slightly when placing a horizontal roll in a machine.
A swing frame type paper roll clamp, such as the paper roll clamp disclosed in House, U.S. Pat. No. 4,435,119, enables the clamp arms on opposing sides of the clamping attachment to be moved toward or away from the vehicle. A rotator is attached to a lift truck or other vehicle and a face plate of the swing frame clamp is attached to the rotator's bearing on the side farthest from the lift vehicle. The face plate is a large monolithic plate including a number of holes for fasteners to secure the face plate to the rotator's bearing and defining a large central aperture in which a revolving hydraulic connection is mounted. Upper and lower subframes, having, generally, I-beam cross-sections, are each pivotally attached to the face plate by pins which engage respective pairs of support blocks welded to and projecting from the face plate above and below each subframe. The clamp arms are pivotally attached to the subframes and are pivoted to clamp or release a load by hydraulic clamping rams which are, respectively, connected to a clamp arm and one of the subframes. Extension or retraction of a swing frame hydraulic ram attached to the face plate and the subframes pivots the subframes about their central connections to the faceplate to swing the opposing ends of the subframes and the attached clamp arms nearer or farther from the lift truck.
Hydraulic fluid from the lift truck flows through the revolving hydraulic connection at the center of the face plate and thence in conduits arrayed across the surface of the face plate to the various hydraulic rams of the clamp. The eight conduits which supply hydraulic fluid to the clamping rams are complex each comprising a U-shaped tubing portion which is connected to a flexible hose portion. Each tube portion includes a first length of tubing extending away the central revolving hydraulic connection toward the side of the face plate opposite of the clamping ram to which the conduit will ultimately be connected. A second length of tubing extends normal to the first length toward either the top or the bottom of the face plate. A relief is provided in a portion the innermost flange of each subframe, on both sides of the central pivot, so that the second lengths of tubing can extend from the middle of the face plate to a point behind the web of the I-shaped subframe. A third length of tubing, bent normal to the second length, extends the conduit behind the web of the respective subframe toward the lateral center of the face plate where the tubing is attached to a hose which is connected to one of the clamping rams. The hose permits the conduits to conform to the movements of the clamping rams as they swing relative to the face plate when the clamp arms are pivoted. The relief in the subframe's flange to accommodate the conduits supplying the clamping rams concentrates stress in the flange and the conduits are difficult to access for assembly or repair, such as replacing a worn hose portion, because they are attached to the face plate behind the subframes.
What is desired is a swing frame paper roll clamp with a face plate that is simpler and less costly to manufacture and enables a less complicated and less intrusive hydraulic fluid connection to the clamping rams.